1. Filed of Industrial Application:
The present invention relates to a silencer for a pneumatically driven hydraulic jack and more particularly to a silencer for suppressing the exhaust noise of an air motor for driving a hydraulic jack.
2. Description of the Prior Art:
In a conventional pneumatically driven hydraulic jack, compressed air of a high pressure, for example, 6 to 10 kg/cm.sup.2, is discharged from the air motor through the discharge port during the return travel of the piston of the air motor. Accordingly, in the normal operating state, the air motor generates an exhaust noise of 90 dB or greater as measured 1 m away from the air motor, which is a noise exceeding an allowable limit.
A device for suppressing such an exhaust noise is disclosed, for example, in U.S. Pat. No. 4,093,406. This device is constituted so as to discharge air indirectly into the atmosphere through a plurality of baffleplates to suppress the exhaust noise. This device, however, has disadvantages that the construction is complex and expensive and the resistance of the baffleplates to the air passing therethrough affects adversely to the efficiency of the associated apparatus.